In a gas-insulated switching apparatus for use at a substation and a generating station, which are electric power stations, voltage is applied to main buses of three phases that are a U phase, a V phase, and a W phase. Divergence buses diverge from the main buses of the three phases, and circuit breakers and disconnect switches for interrupting current are connected to the divergence buses. The main buses, the divergence buses, the circuit breakers, and the disconnect switches are housed inside a tank filled with an insulating gas, so that insulation of a main circuit is maintained.
The circuit scheme of gas-insulated switching apparatuses includes a circuit scheme of what is called a double bus scheme in which one divergence bus is drawn from two main buses. Additionally, there are gas-insulated switching apparatuses of a three-phase-integrated type in which conductors of the three phases are housed together inside a tank, and gas-insulated switching apparatuses of a three-phase-isolated type in which conductors of the three phases are housed in separate tanks, as disclosed in Patent Literature 1.